Separation of tetrachloroethylene from a butyl alcohol by extractive distillation

Abstract

Tetracholorethylene cannot be completely separated from n-butanol, isobutanol or 2-butanol by conventional distillation or rectification because of minimum boiling azeotropes. Tetrachloroethylene can be readily separated from n-butanol, isobutanol or 2-butanol by extractive distillatiion. Typical effective agents are: for n-butanol, dipropylene glycol methyl ether; for isobutanol, dimethylsulfoxide and isobutyl butyrate; for 2-butanol, ethylene glycol methyl ether and isobornyl acetate.

I claim: 
     
       1. A method for recovering tetrachloroethylene from a mixture of tetrachloroethylene and n-butanol which comprises distilling a mixture of tetrachloroethylene and n-butanol in the presence of about one part of an extractive agent per part of tetrachloroethylene-n-butanol mixture, recovering the tetrachloroethylene as overhead product and obtaining the n-butanol and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of diethylene glycol ethyl ether, 1-methoxy-2-propanol, ethyl 3-ethoxypropionate, butoxypropanol, dipropylene glycol methyl ether, diethylene glycol methyl ether, 1-methoxy-2-propanol acetate, ethylene glycol butyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol isobutyl ether, ethylene glycol phenyl ether, 4-methoxy-4-methyl pentanone-2, propoxypropanol and mesityl oxide. 
     
     
       2. A method for recovering tetrachloroethylene from a mixture of tetrachloroethylene and isobutanol which comprises distilling a mixture of tetrachloroethylene and isobutanol in the presence of about one part of an extractive agent per part of tetrachloroethylene-isobutanol mixture, recovering tetrachloroethylene as overhead product and obtaining the isobutanol and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of 1-methoxy-2-propanol acetate, dimethylsulfoxide, dimethylformamide, dimethylacetamide and sulfolane. 
     
     
       3. A method for recovering isobutanol from a mixture of isobutanol and tetrachloroethylene which comprises distilling a mixture of isobutanol and tetrachloroethylene in the presence of about one part of isobutanol-tetrachloroethylene mixture, recovering the isobutanol as overhead product and obtaining the tetrachloroethylene and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of ethyl isovalerate, ethyl butyrate, n-amyl acetate, hexyl formate, 4-methyl pentyl acetate-2, 2-ethyl hexyl acetate, methyl caproate, methyl benzoate, ethyl benzoate, ethylene glycol butyl ether acetate, isobutyl butyrate, isobutyl isobutyrate, 3-heptanone, isobutyl heptyl ketone and acetophenone. 
     
     
       4. A method for recovering tetrachloroethylene from a mixture of tetrachloroethylene and 2-butanol which comprises distilling a mixture of tetrachloroethylene and 2-butanol in the presence of about one part of an extractive agent per part of tetrachloroethylene-2-butanol mixture, recovering tetrachloroethylene as overhead product and obtaining the 2-butanol and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol hexyl ether, diethylene glycol methyl ether, 4-methyl-2-pentanone, isophorone and dipropylene glycol methyl ether acetate. 
     
     
       5. A method for recovering 2-butanol from a mixture of 2-butanol and tetrachloroethylene which comprises distilling a mixture of 2-butanol and tetrachloroethylene in the presence of about one part of 2-butanol-tetrachloroethylene mixture, recovering the 2-butanol as overhead product and obtaining the tetrachloroethylene and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of ethyl valerate, isobutyl butyrate, ethyl isovalerate, isobutyl isobutyrate, ethyl butyrate, hexyl formate, isobornyl acetate, diethylene glycol hexyl ether, ethylene glycol ethyl ether acetate, 4-methyl pentyl acetate-2, and hexyl acetate.